1. Technical Field
The present invention generally relates to an electronic system having a programmable input/output interface, and more particularly, relates to a method for stably maintaining operation of such an electronic system against static electricity.
2. Related Art
Portable electronic systems such as hand held calculators, telephones, cameras, wristwatches, mini-computers, electronic typewriters, and those electronic devices that are not grounded but contain sensitive electronic, magnetic circuits and/or memories, are prone to erroneous operation due to static electricity.
Generally, there are many available techniques used to protect an electronic system from erroneous operation due to static electricity. These techniques typically include means to deflect or dissipate the electrostatic discharge emanating from the user to the system. For example, in U.S. Pat. No. 3,935,508 for High Voltage Discharge Switch For Protecting Sensitive Electronic Equipment And The Operators Thereof Moister, Jr. discloses an electronic system having a discharge switch formed of an electrically conductive material connected to a chassis of the electronic system for dissipating a charge of static electricity from the user. In U.S. Pat. No. 4,752,862 for Electronic Device, Takahashi et al., discloses a metal housing structure which is made of an insulating material for protecting an electronic system from erroneous operation due to static electricity. U.S. Pat. No. 4,821,320 for Device For Protecting Electrical Apparatus And The Operator When The Operator Carries A High Electrostatic Charge issued to Andert et al., provides a resistance path arranged to lead the electrostatic discharge from the user to a ground potential point of the electronic system. U.S. Pat. No. 4,844,630 for Method And Circuit Arrangement For Protection Of Typewriters Or Similar Machines Against Consequences OfElectrostatic Discharge issued to Hagen et al., discloses an electronic typewriter which uses a cover switch to reset operation of a microprocessor for operation protection against a consequence of an electrostatic discharge. U.S. Pat. No. 5,123,102 for Method And Apparatus For Suspending Computation Due To Detection Of Electrostatic Discharge issued to Puckette, discloses a digital hand held calculator which uses an edge detector for detecting a leading edge of an electrostatic discharge and an internal wait circuitry for suspending operation of a microprocessor for a predetermined time period before an electrostatic discharge can disturb operation of the microprocessor. U.S. Pat. No. 5,401,926 for Data Input Device With A Manually Operable Key Having Static Electricity Releasing Function issued to Aoyama et al., discloses an electronic system which uses a static electricity releasing circuit formed from a manually operable keytop of a keyboard to a ground in order to instantaneously release static electricity that has accumulated from the user to the ground.
While the contemporary electrostatic discharge techniques for modern electronic systems are valued, I have observed however, that a simpler technique for protecting an electronic system from erroneous operation due to static electricity can be contemplated.